Located on the Deli River near the city of Medan, Belawan is Indonesia's busiest port outside of Java. Visitors to Medan enjoy seeing the Great Mosque (the largest in Sumatra) and the beautiful Palace of the Sultan of Deli. Medan was originally settled by Dutch colonists, and many old buildings in the area still retain their Dutch architecture, including the old City Hall, the central Post Office, the Tirtanadi Water Tower, which is Medan City's icon, and Titi Gantung (a bridge over the railway). Visitors may wish to explore more of the area beyond the port by taking advantage of the regular ferry service to Penang, Malaysia.